/** Returns the approximate number of entries in this cache. */
  long size();

  /**
   * Returns a current snapshot of this cache's cumulative statistics, or a set of default values if
   * the cache is not recording statistics. All statistics begin at zero and never decrease over the
   * lifetime of the cache.
   *
   * <p><b>Warning:</b> this cache may not be recording statistical data. For example, a cache

        }
    }

    /**
     * Sends email notification with crawling results and statistics.
     * The email contains detailed information about the crawling session including
     * execution times, index sizes, and status information.
     *
     * @param infoMap map containing crawling session information and statistics
     */
    protected void sendMail(final Map<String, String> infoMap) {

import java.util.Locale;
import java.util.Properties;

import org.apache.maven.impl.util.Os;
import org.apache.maven.jline.MessageUtils;
import org.slf4j.Logger;

/**
 * Utility class used to report errors, statistics, application version info, etc.
 *
 */
public final class CLIReportingUtils {
    // CHECKSTYLE_OFF: MagicNumber
    public static final long MB = 1024 * 1024;

    private static final long ONE_SECOND = 1000L;

 * may cause corruption or runtime errors if not. It may however be shared amongst multiple OkHttpClient
 * instances.
 *
 * ## Cache Optimization
 *
 * To measure cache effectiveness, this class tracks three statistics:
 *
 *  * **[Request Count:][requestCount]** the number of HTTP requests issued since this cache was
 *    created.
 *  * **[Network Count:][networkCount]** the number of those requests that required network use.

## Review PRs

* If a PR doesn't explain what it does or why, if it seems like it could be useful, ask for more information. Otherwise, feel free to close it.

* If a PR seems to be spam, meaningless, only to change statistics (to appear as "contributor") or similar, you can simply mark it as `invalid`, and it will be automatically closed.

  }

  @Override
  @J2ktIncompatible // Thread safety complexity
  public ConcurrentMap<K, V> asMap() {
    throw new UnsupportedOperationException();
  }

  /**
   * Accumulates statistics during the operation of a {@link Cache} for presentation by {@link
   * Cache#stats}. This is solely intended for consumption by {@code Cache} implementors.
   *
   * @since 10.0
   */
  public interface StatsCounter {

    public static final String USER_CODE = "userCode";

    /** Search query field name for logging. */
    public static final String SEARCH_FIELD_LOG_SEARCH_QUERY = "q";

    /** Statistics report type parameter name. */
    public static final String STATS_REPORT_TYPE = "reportType";

    /** Result document ID cache key. */
    public static final String RESULT_DOC_ID_CACHE = "resultDocIds";

 *   <li>values automatically wrapped in {@linkplain WeakReference weak} or {@linkplain
 *       SoftReference soft} references
 *   <li>notification of evicted (or otherwise removed) entries
 *   <li>accumulation of cache access statistics
 * </ul>
 *
 * <p>These features are all optional; caches can be created using all or none of them. By default,
 * cache instances created by {@code CacheBuilder} will not perform any type of eviction.
 *

@NullUnmarked
@J2ktIncompatible
@GwtIncompatible
class StatsTesting {
  // TODO(cpovirk): Convince myself that this larger error makes sense.
  static final double ALLOWED_ERROR = isAndroid() ? .25 : 1e-10;

  // Inputs and their statistics:

  static final double ONE_VALUE = 12.34;

  static final double OTHER_ONE_VALUE = -56.78;

  static final ImmutableList<Double> TWO_VALUES = ImmutableList.of(12.34, -56.78);

@NullUnmarked
@J2ktIncompatible
@GwtIncompatible
class StatsTesting {
  // TODO(cpovirk): Convince myself that this larger error makes sense.
  static final double ALLOWED_ERROR = isAndroid() ? .25 : 1e-10;

  // Inputs and their statistics:

  static final double ONE_VALUE = 12.34;

  static final double OTHER_ONE_VALUE = -56.78;

  static final ImmutableList<Double> TWO_VALUES = ImmutableList.of(12.34, -56.78);